The present invention relates to a method of cleaning residual dye material from rollers of a textile fabric drying oven, and more particularly to such a method performed during passage of a traveling cloth lead therethrough.
In conventional oven drying of fabrics in a dyeing range it is common for the rollers over which the wet or moist fabric passes before the fabric is substantially dry to have dye material from the fabric deposited on the rollers. This deposition results from the fabric being more or less wet from the liquor application. The degree of residual moisture, and therefore the degree of dye deposition as well as the number of rollers on which the deposition occurs, depends on the pretreatment, including squeezing, and any preliminary drying. For example, if the dye is applied to the fabric in a padder and then squeezed, the residual moisture at the discharge of the squeezing unit may be in the range of between 40% and 100% depending on the material and the type and extent of treatment, on the other hand, if the dyeing oven is preceded by an infrared preliminary dryer, a residual moisture in the range of approximately 20% to 40% may be common. Deposition of dye material from the fabric onto the rollers generally ceases at the point in the oven where the moisture in the fabric has been decreased to below about 5% to 20% depending on the type of fabric material, dye and dye liquor.
The manner in which the dye liquor, particularly aqueous, is applied to the fabric is not pertinent to the present invention. Any kind of dye liquor application or equipment can be used, for example, a padder, a sprayer, a foam applicator or a low liquor ratio applicator, the latter being of particular use for applying dye to one side of a fabric.
When the color or type of dye material to be applied is changed from one run to the next, not only does the liquor applicator unit have to be cleaned but also the oven itself must be cleaned to remove residual dye material of the preceding dyeing from the rollers on which the material has been deposited. The conventional practice is for the individual rollers to be cleaned by an operator working from the side of the equipment in a manner that does not significantly disturb the threading of the cloth lead through the equipment. This is a tedious and time-consuming task not uncommonly requiring two or more hours.
To minimize the number of cleanings that must be performed, it is often the practice not to change colors or dyeing operations randomly. Rather, it is common to start dyeing cycles on a Monday, for example, with pale dyes and during the progress of the week change to increasingly darker dye applications. In this manner thorough cleaning of the rollers is not necessary until the end of the sequence of dye cycles and before a new cycle begins with pale dyes. However, this practice is not possible for dyeing operations where, as is often the case, priority of delivery and short notice orders prevent orderly planning of dyeing from pale to dark shades over an extended cycle period.